Yesterday, Duckworth blasted Kirk for his refusal to distance himself from Trump after the presumptive nominee’s racist attacks against federal judge Gonzalo Curiel, who is presiding over two class action lawsuits by former students at Trump University.

“Trump’s statements are outrageous. They are un-American and they are dangerous. They betray the weaknesses of a man who is fundamentally unsuited for the office of the presidency,” Duckworth told about 200 people, according to the Chicago Tribune.

A month ago, Kirk said that Trump’s candidacy would be “a net benefit” for his Senate re-election, referencing the large numbers of Republican primary voters he was bringing out to polls. He said at that time that he would endorse the Republican nominee for president, but that he was confident voters would be able to separate his candidacy from Trump’s

“These days I’m probably the best-positioned Republican to weather the institution of Trumpism because I have been voting pro-gay rights and against the gun lobby and solidly pro-choice,” Kirk said in the CNN interview at the time.

Read Kirk’s full statement to the press on his un-endorsement below:

“I have spent my life building bridges and tearing down barriers–not building walls. That’s why I find Donald Trump’s belief that an American-born judge of Mexican descent is incapable of fairly presiding over his case is not only dead wrong, it is un-American.

“As the Presidential campaign progressed, I was hoping the rhetoric would tone down and reflect a campaign that was inclusive, thoughtful and principled. While I oppose the Democratic nominee, Donald Trump’s latest statements, in context with past attacks on Hispanics, women and the disabled like me, make it certain that I cannot and will not support my party’s nominee for President regardless of the political impact on my candidacy or the Republican Party.

“It is absolutely essential that we are guided by a commander-in-chief with a responsible and proper temperament, discretion and judgment. Our President must be fit to command the most powerful military the world has ever seen, including an arsenal of thousands of nuclear weapons. After much consideration, I have concluded that Donald Trump has not demonstrated the temperament necessary to assume the greatest office in the world.”

Sen. Mark Kirk (R-Ill.), who’s up for re-election this year, has an incentive to appear as moderate and level-headed as possible. He is, after all, a Republican running in a pretty blue state, sharing a ballot with Donald Trump in a presidential election year. The circumstances have made Kirk arguably the Senate’s most endangered incumbent.

And yet, the GOP senator just keeps making bizarre comments. Politicoreports today:

U.S. Sen. Mark Kirk hasn’t let up on his insistence that President Obama is using his power as president to lash out at a political enemy.

At a fundraising event last month in Chicago, the Illinois Republican can be heard on audio defending indicted New Jersey Senator Bob Menendez, a Democrat, while accusing Obama of targeting Menendez because of his stance on Iran.

According to a recording Politico obtained, Kirk told his audience, “And let me say something about Bob Menendez. I believe that Bob Menendez was indicted solely on the crime of opposing the president on Iran.”

It wasn’t an off-hand comment: the Illinois Republican has pushed the same conspiracy theory over and over again.

To the extent that reality matters, we know that Kirk is completely wrong. The corruption investigation into Menendez’s work initiated long before the Iran deal negotiations even began, and the indictment was issued before the Iran deal was finalized. Besides, Menendez’s opposition to the international agreement was inconsequential, so the White House has no incentive to punish him.

But even if we put that aside, what Kirk is arguing is that the White House orchestrated an elaborate conspiracy, involving multiple federal prosecutors and investigators over the course of several years, to seek retribution against a senator from the president’s own party, who generally agrees with the administration’s position on most issues.

As proof, Kirk points to … nothing. The Illinois Republican believes the White House is guilty of an impeachable offensive, manipulating federal law enforcement to execute a partisan retribution scheme, as a result conspiracy theory that doesn’t make sense. The senator is comfortable throwing around this accusation, repeatedly and in public, despite having literally no evidence whatsoever.

Senators generally aren’t supposed to behave this way. Senators worried about their re-election bids never behave this way.

And circling back to a report from last summer, there’s also the larger pattern of Mark Kirk’s bizarre rhetoric as the election draws closer. When congressional Republicans threatened to shut down the Department of Homeland Security last year, it was the Illinois senator who got a little hysterical, urging the GOP to “build a number of coffins outside each Democratic office.”

In isolation, these bizarre incidents might be easier to dismiss as regrettable slip-ups, but taken together, a pattern emerges of a senator who once claimed moderation, but not anymore.

If there’s an electoral strategy that explains such behavior, I can’t think of it. Kirk should be going out of his way to appear sensible, but for reasons no one seems able to explain, the GOP senator is doing the opposite.

I know the air is filled with Republican hysteria about the Iran nuclear deal, but it’s still possible to distinguish honest disagreement on a complex topic with politically motivated or just plain crazy treatment of this highly contingent multilateral agreement as one of the worst moments in human history. I mean, it’s one thing to talk about acceptable and unacceptable risks, but some of these birds are acting as though the missiles aimed at Tel Aviv are being armed as we speak.

With that in mind, read this series of quotes served up by Buzzfeed‘s Andrew Kaczynski and see if you can figure out who might have uttered them:

“This agreement condemns the next generation to cleaning up a nuclear war in the Persian Gulf,” ____ said. “It condemns our Israel allies to further conflict with Iran.” ____ added that he thought the agreement will yield “more nukes, and more terrorists, and more irresponsibility by the Iranians,” saying he thought Iran will now increase their influence in Iraq and Yemen.

“This is the greatest appeasement since Chamberlain gave Czechoslovakia to Hitler,” ____ continued, saying he believed Obama only went through with the deal because he has a poor understanding of history and did not realize appeasement made war more likely. _____ said he thought the deal meant that Israel would now have to take “military action against Iran.”

“The president will make this a viciously partisan issue, leading most Democrats to standing with the Iranians and hopefully losing the next election on this point,” ____ said. “He will ask the Democrats all to stand with Iran and make sure that we can’t get two-thirds majorities in the House and Senate.”

Asked if any Democrats disagreed with the president, ____ pointed to New York Sen. Chuck Schumer and New Jersey Democrat Bob Menendez, who he believed “has just been indicted maybe on the crime of being against the Iran deal.”

____ said he believed the only reason the president supported legislation from Republican Sen. Bob Corker, the chair of the Foreign Relations Committee, that allowed Congress to review the deal was because he “wants…to get nukes to Iran.”

No, it’s the junior senator from Illinois, Mark Kirk, often described as a “centrist” or a “moderate,” and universally thought of as the most endangered U.S. Senator going into his 2016 reelection race.

I guess this could be some ploy to pursue Jewish voters, though there wouldn’t be this whole meme about Netanyahu’s war with American Jews if that sort of talk was widely popular with Jewish folk. Or maybe he’s making up for lost gabbing after his recovery from a stroke. But it’s weird to see a statewide elected official from the president’s home state–a blue state at that–basically accuse him of deliberate assistance to terrorists right before voters consider him for another term.